Cadence and performance in elite cyclists

Many studies have attempted to describe the optimal cadence in cycling. However, the effect on performance has received little attention. The aim of the present study was therefore to examine the effect of cadence on performance during prolonged cycling (~30 min). Fourteen male elite cyclists performed two or five time trials at different cadences [60, 80, 100, 120 rpm or freely chosen cadence (FCC)]. The total work was the same between the time trials, and the subjects were instructed to complete each time trial as fast as possible by adjusting the workload with buttons mounted on the handlebar. Accumulated work and cadence was visualised on a monitor. Oxygen uptake was measured continuously and blood lactate concentration every fifth minute. Compared to 80 rpm, finishing times at 60, 100 and 120 rpm were 3.5, 1.7 and 10.2% slower (P<0.05). Finishing time at FCC (mean 90 rpm) was indistinguishable from 80 and 100 rpm. Gross efficiency at 80 rpm was 2.9, 2.3, 3.4 and 12.3% larger than at 60, FCC, 100 and 120 rpm, respectively (P<0.05). The maximal energy turnover rate was 1.7% higher at 100 than at 80 rpm (P<0.05). This could not, however, compensate for the 3.4% lower efficiency at 100 rpm. This study demonstrated that elite cyclists perform best at their most efficient cadence despite the maximal energy turnover rate being larger at a higher cadence.     

Effect of isokinetic cycling versus weight training on maximal power output and endurance performance in cycling

The aim of this study was to compare the effects of a weight training program for the leg extensors with isokinetic cycling training (80 rpm) on maximal power output and endurance performance. Both strength training interventions were incorporated twice a week in a similar endurance training program of 12 weeks. Eighteen trained male cyclists (VO_2peak 60 ± 1 ml kg⁻¹ min⁻¹) were grouped into the weight training (WT n = 9) or the isokinetic training group (IT n = 9) matched for training background and sprint power (P _max), assessed from five maximal sprints (5 s) on an isokinetic bicycle ergometer at cadences between 40 and 120 rpm. Crank torque was measured (1 kHz) to determine the torque distribution during pedaling. Endurance performance was evaluated by measuring power, heart rate and lactate during a graded exercise test to exhaustion and a 30-min performance test. All tests were performed on subjects’ individual race bicycle. Knee extension torque was evaluated isometrically at 115° knee angle and dynamically at 200° s⁻¹ using an isokinetic dynamometer. P _max at 40 rpm increased in both the groups (~15%; P < 0.05). At 120 rpm, no improvement of P _max was found in the IT training group, which was possibly related to an observed change in crank torque at high cadences (P < 0.05). Both groups improved their power output in the 30-min performance test (P < 0.05). Isometric knee extension torque increased only in WT (P < 0.05). In conclusion, at low cadences, P _max improved in both training groups. However, in the IT training group, a disturbed pedaling technique compromises an improvement of P _max at high cadences.     

Freely chosen pedal rate during free cycling on a roller and ergometer cycling

The purpose of this study was to examine the effect of regulation of work rate, computer controlled versus controlled by the subject, on the relationship between work rate, freely chosen pedal rate (FCC) and gross efficiency. Eighteen male cyclists participated in the study. One group, freely cycling (FC) on a competition bike mounted on an electromagnetic roller, could use gearing and cadence to achieve each work rate. The other group (EC) was cycling on an ergometer which enables a constant work rate, independent of cadence. Subjects performed an increasing work rate protocol from 100 W up to exhaustion. We found a strong interaction between group and work rate on cadence (P < 0.001). In the FC group, work rate affected cadence (P < 0.001), increasing from 72 rpm at 100 W to 106 rpm at 350 W. For the EC group, no work rate effect was present (average FCC 92 rpm). Gross efficiency increased with work rate for both groups. The efficiency–cadence relationship was strongly affected by the protocol. At a given work rate, very similar efficiency values were obtained at highly different cadences. The discrepancy in the FCC-work rate relationship between the EC group and the FC group may be related to the manner in which one can regulate work rate. FCC depends not only on work rate but is also affected considerably by the manner in which the work rate can be controlled by cadence. This finding may have important implications for the interpretation of the preferred pedaling rate, especially how this is related to optimizing metabolic cost.     

Aerobic power and peak power of elite America’s Cup sailors

Big-boat yacht racing is one of the only able bodied sporting activities where standing arm-cranking (‘grinding’) is the primary physical activity. However, the physiological capabilities of elite sailors for standing arm-cranking have been largely unreported. The purpose of the study was to assess aerobic parameters, VO_2peak and onset of blood lactate (OBLA), and anaerobic performance, torque–crank velocity and power–crank velocity relationships and therefore peak power (P _max) and optimum crank-velocity (ω_opt), of America’s Cup sailors during standing arm-cranking. Thirty-three elite professional sailors performed a step test to exhaustion, and a subset of ten grinders performed maximal 7 s isokinetic sprints at different crank velocities, using a standing arm-crank ergometer. VO_2peak was 4.7 ± 0.5 L/min (range 3.6–5.5 L/min) at a power output of 332 ± 44 W (range 235–425 W). OBLA occurred at a power output of 202 ± 31 W (61% of W_max) and VO₂ of 3.3 ± 0.4 L/min (71% of VO_2peak). The torque–crank velocity relationship was linear for all participants (r = 0.9 ± 0.1). P _max was 1,420 ± 37 W (range 1,192–1,617 W), and ω_opt was 125 ± 6 rpm. These data are among the highest upper-body anaerobic and aerobic power values reported. The unique nature of these athletes, with their high fat-free mass and specific selection and training for standing arm cranking, likely accounts for the high values. The influence of crank velocity on peak power implies that power production during on-board ‘grinding’ may be optimised through the use of appropriate gear-ratios and the development of efficient gear change mechanisms.     

Power-cadence relationship in endurance cycling

In maximal sprint cycling, the power–cadence relationship to assess the maximal power output (P _max) and the corresponding optimal cadence (C _opt) has been widely investigated in experimental studies. These studies have generally reported a quadratic power–cadence relationship passing through the origin. The aim of the present study was to evaluate an equivalent method to assess P _max and C _opt for endurance cycling. The two main hypotheses were: (1) in the range of cadences normally used by cyclists, the power–cadence relationship can be well fitted with a quadratic regression constrained to pass through the origin; (2) P _max and C _opt can be well estimated using this quadratic fit. We tested our hypothesis using a theoretical and an experimental approach. The power–cadence relationship simulated with the theoretical model was well fitted with a quadratic regression and the bias of the estimated P _max and C _opt was negligible (1.0 W and 0.6 rpm). In the experimental part, eight cyclists performed an incremental cycling test at 70, 80, 90, 100, and 110 rpm to yield power–cadence relationships at fixed blood lactate concentrations of 3, 3.5, and 4 mmol L⁻¹. The determined power outputs were well fitted with quadratic regressions (R ² = 0.94–0.96, residual standard deviation = 1.7%). The 95% confidence interval for assessing individual P _max and C _opt was ±4.4 W and ±2.9 rpm. These theoretical and experimental results suggest that P _max, C _opt, and the power–cadence relationship around C _opt could be well estimated with the proposed method.     

Aerobically trained individuals have greater increases in rectal temperature than untrained ones during exercise in the heat at similar relative intensities

To determine if the increases in rectal temperature (T _REC) during exercise in the heat at a given percent of [(V)\dot]O_2 \textpeak \dot{V}\hbox{O}_{{2\,{\text{peak}}}} depend on a subject’s aerobic fitness level. On three occasions, 10 endurance-trained (Tr) and 10 untrained (UTr) subjects ([(V)\dot]O_2 peak \dot{V}\hbox{O}_{2\,{\rm peak}} : 60 ± 6 vs. 44 ± 3 mL kg⁻¹ min⁻¹, P < 0.05) cycled in a hot-dry environment (36 ± 1°C; 25 ± 2% humidity, airflow 2.5 m s⁻¹) at three workloads (40, 60, and 80% [(V)\dot]O_2 peak \dot{V}\hbox{O}_{2\,{\rm peak}} ). At the same percent of [(V)\dot]O_2 peak \dot{V}\hbox{O}_{2\,{\rm peak}} , on average, Tr had 28 ± 5% higher heat production but also higher skin blood flow (29 ± 3%) and sweat rate (20 ± 7%; P = 0.07) and lower skin temperature (0.5°C; P < 0.05). Pre-exercise T _REC was lower in the Tr subjects (37.4 ± 0.2 vs. 37.6 ± 0.2; P < 0.05) but similar to the UTr at the end of 40 and 60% [(V)\dot]O_2 peak \dot{V}\hbox{O}_{2\,{\rm peak}} trials. Thus, exercise T _REC increased more in the Tr group than in the UTr group (0.6 ± 0.1 vs. 0.3 ± 0.1°C at 40% [(V)\dot]O_2 peak \dot{V}\hbox{O}_{2\,{\rm peak}} and 1.0 ± 0.1 vs. 0.6 ± 0.3°C at 60% [(V)\dot]O_2 peak \dot{V}\hbox{O}_{2\,{\rm peak}} ; P < 0.05). At 80% [(V)\dot]O_2 peak \dot{V}\hbox{O}_{2\,{\rm peak}} not only the increase in T _REC (1.7 ± 0.1 vs. 1.3 ± 0.3°C) but also the final T _REC was larger in Tr than in UTr subjects (39.15 ± 0.1 vs. 38.85 ± 0.1°C; P < 0.05). During exercise in the heat at the same relative intensity, aerobically trained individuals have a larger rise in T _REC than do the untrained ones which renders them more hyperthermic after high-intensity exercise.     

The energetically optimal cadence decreases after prolonged cycling exercise

This study investigated the change in the energetically optimal cadence after prolonged cycling. The energetically optimal cadence (EOC) was determined in 14 experienced cyclists by pulmonary gas exchange at six different cadences (100–50 rpm at 10 rpm intervals). The determination of the EOC was repeated after a prolonged cycling exercise of 55 min duration, where cadence was fixed either at high (>95 rpm) or low (<55 rpm) pedalling rates. The EOC decreased after prolonged cycling exercise at a high as well as at a low fixed cadence (P < 0.01). According to the generalized muscle equations of Hill, this indicates that most likely more type I muscle fibres contribute to muscular power output after fatiguing cycling exercise compared to cycling in the beginning of an exercise bout. We suggest that the determination of EOC might be a potential non-invasive method to detect the qualitative changes in activated muscle fibres, which needs further investigation.     

The most economical cadence increases with increasing workload

Several studies have suggested that the most economical cadence in cycling increases with increasing workload. However, none of these studies have been able to demonstrate this relationship with experimental data. The purpose of this study was to test the hypothesis that the most economical cadence in elite cyclists increases with increasing workload and to explore the effect of cadence on performance. Six elite road cyclists performed submaximal and maximal tests at four different cadences (60, 80, 100 and 120 rpm) on separate days. Respiratory data was measured at 0, 50, 125, 200, 275 and 350 W during the submaximal test and at the end of the maximal test. The maximal test was carried out as an incremental test, conducted to reveal differences in maximal oxygen uptake and time to exhaustion (short-term performance) between cadences. The results showed that the lowest oxygen uptake, i.e. the best work economy, shifted from 60 rpm at 0 W to 80 rpm at 350 W (P<0.05). No difference was found in maximal oxygen uptake among cadences (P>0.05), while the best performance was attained at the same cadence that elicited the best work economy (80 rpm) at 350 W (P<0.05). This study demonstrated that the most economical cadence increases with increasing workload in elite cyclists. It was further shown that work economy and performance are related during short efforts (~5 min) over a wide range of cadences.     

Influence of cycling cadence on neuromuscular activity of the knee extensors in humans

The aim of the present study was to investigate the influence of pedalling rate and power output in cycling on the neuromuscular activity of the knee extensor muscles. Ten subjects took part in 15 randomised trials, which consisted of three levels of power outputs (60%, 80% and 100% maximal aerobic power) and five cadences (70%, 85%, 100%, 115% and 130% of the freely chosen cadence, FCC). Root mean square (rms) was utilized to quantify electromyographic activity of the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) muscles. The mean (SD) FCC did not change with power output, ranging from 85.0 (11.9) to 88.0 (11.1) rpm. A significant power effect (P<0.01) for the rms of VL, VM and RF muscles was observed. Results showed no significant cadence effect on neuromuscular activity of the VL and VM muscles, while the rms of the RF muscle was significantly greater (P<0.05) at 70% FCC when compared to other cadences. In conclusion, the neuromuscular activity of the knee extensor muscles was not significantly influenced by cadence manipulations. Thus, minimisation of the neuromuscular activity of these muscles would not seem to lead to the choice of a cadence in cycling. Electronic Publication     

Cycling performance and mechanical variables using a new prototype chainring

The primary aim of our study was to examine supra-maximal cycling performance and related mechanical variables in trained cyclists using a new prototype chainring (PC) designed to produce a higher mean net torque (T _{N mean}) than a standard chainring (SC). The main feature of the PC is that crank-arm alignment and lever-arm length change as a function of the crank angle during the pedaling cycle. The PC presents two features theorized to effect cycling performance: (1) out of line of pedal cranks resulting in an decrease in the dead points, and (2) a change in crank arm length inducing a torque different from that of SC during the down- and up-stroke of the pedaling cycle. To investigate this theory, we examined eight male cyclists who performed a 1-km “all-out” cycling test in the following order: SC, PC, and SC. Performance was measured as the time (s) to complete the 1-km test. Mechanical variables included torque (N m⁻¹), crank velocity (rad s⁻¹), and power output (W). We performed our statistical analysis using a two-way ANOVA for repeated measurements and Newman–Keuls post hoc assessment. Our results showed that performance was similar for SC (69.41 ± 6.69 s) and PC (73.33 ± 4.58 s). Torque, crank velocity, and power output were also similar throughout (P > 0.05). We conclude that despite the theoretically benefits proposed by the inventors the new PC investigated in our study failed to improve cycling performance or mechanical variables during a supramaximal test when compared with SC.     

Propulsion technique in hand rim wheelchair ambulation

Six male subjects took part in a pilot study on a stationary wheelchair ergometer. They propelled the ergometer at a speed of 0·55, 0·83, 1·11 and 1·39 m/s. The speed increased every 3 min. Inertia and friction force were adjusted proportional to body weight. Every third minute 750 samples of the torque and velocity signals were digitized at a sampling rate of 100 Hz. From the signals mean external power output (P_mean), peak power (P_peak), mean torque (M_mean) and peak torque (M_peak), work/cycle, ‘time-to-peak torque’ (TTP), cycle duration (CT), push time (PT) and recovery time (RT) were determined in relation to mean velocity (speed).

For the mean velocity range studied, analysis of variance (P > 0·05) revealed significant increments in P_peak, M_peak, P_means, M_mean and work/cycle with increasing mean velocity, whereas CT and PT showed a significant decrease. TTP showed a decrease with speed which, however, was not statistically significant. The RT showed no significant variation as well. Our previous research into propulsion techniques mainly focused on movement frequency and timing and was conducted during wheelchair ambulation on a motor driven treadmill. Despite considerable interindividual variation in terms of movement pattern, current and previous studies showed similar trends in the timing pattern (cycle, push, recovery duration) with respect to speed. Theoretical considerations regarding variations in peak torque and work/cycle with respect to velocity are supported by the current results. Both torque and work/cycle are important technique parameters and of relevance in speed regulation. The data also suggest that wheelchair ambulation can be validly simulated and studied with the special purpose wheelchair ergometer. Between-subject variation suggests the effect of wheeling experience and needs further research.     

The relationship between cadence,pedalling technique and gross efficiency in cycling

Technique and energy saving are two variables often considered as important for performance in cycling and related to each other. Theoretically, excellent pedalling technique should give high gross efficiency (GE). The purpose of the present study was to examine the relationship between pedalling technique and GE. 10 well-trained cyclists were measured for GE, force effectiveness (FE) and dead centre size (DC) at a work rate corresponding to ~75% of VO₂max during level and inclined cycling, seat adjusted forward and backward, at three different cadences around their own freely chosen cadence (FCC) on an ergometer. Within subjects, FE, DC and GE decreased as cadence increased (p < 0.001). A strong relationship between FE and GE was found, which was to great extent explained by FCC. The relationship between cadence and both FE and GE, within and between subjects, was very similar, irrespective of FCC. There was no difference between level and inclined cycling position. The seat adjustments did not affect FE, DC and GE or the relationship between them. Energy expenditure is strongly coupled to cadence, but force effectiveness, as a measure for pedalling technique, is not likely the cause of this relationship. FE, DC and GE are not affected by body orientation or seat adjustments, indicating that these parameters and the relationship between them are robust to coordinative challenges within a range of cadence, body orientation and seat position that is used in regular cycling.     

The exercise dose affects oxidative stress and brachial artery flow-mediated dilation in trained men

The aim of this investigation was to establish whether changes in oxidative stress and endothelial function following acute aerobic exercise are dose-dependent. Ten healthy trained men completed four exercise sessions: 50% VO_2peak for 30 min (moderate intensity moderate duration, MIMD), 50% VO_2peak for 60 min (moderate intensity long duration, MILD), 80% VO_2peak for 30 min (high intensity moderate duration, HIMD), and 80% VO_2peak for the time to reach the caloric equivalent of MIMD (high intensity short duration, HISD). Thiobarbituric acid reactive substances (TBARS) were measured as an index of oxidative stress and brachial artery flow-mediated dilation (FMD) was assessed as an index of endothelial function. Variables were measured at baseline, immediately post-exercise, 1 and 2 h post-exercise. Both HIMD (14.2 ± 2.5 μmol/L) and HISD (14.7 ± 1.9 μmol/L) TBARS differed from MIMD (11.8 ± 1.5 μmol/L) immediately post-exercise. TBARS increased from pre to immediately post-exercise for HIMD (12.6 ± 2.1 vs.14.2 ± 2.5 μmol/L) and HISD (12.3 ± 2.8 vs. 14.7 ± 1.9 μmol/L). Both MIMD (7.2 ± 2.2%) and HISD (7.6 ± 2.7%) FMD immediately post-exercise were greater than HIMD (4.7 ± 2.2%). An increase of FMD from pre to immediately post-exercise was found for MIMD (5.0 ± 2.5 vs. 7.2 ± 2.2%) and HISD (5.9 ± 2.4 vs. 7.6 ± 2.7%). These data suggest that acute exercise-induced TBARS are exercise intensity-dependent whereas FMD appears to improve following energy expenditure equivalent to 30 min 50% VO_2peak, regardless of intensity or duration.     

High-intensity interval training improves VO2peak, maximal lactate accumulation, time trial and competition performance in 9–11-year-old swimmers

Training volume in swimming is usually very high when compared to the relatively short competition time. High-intensity interval training (HIIT) has been demonstrated to improve performance in a relatively short training period. The main purpose of the present study was to examine the effects of a 5-week HIIT versus high-volume training (HVT) in 9–11-year-old swimmers on competition performance, 100 and 2,000 m time (T _100 m and T _2,000 m), VO_2peak and rate of maximal lactate accumulation (Lac_max). In a 5-week crossover study, 26 competitive swimmers with a mean (SD) age of 11.5 ± 1.4 years performed a training period of HIIT and HVT. Competition (P < 0.01; effect size = 0.48) and T _2,000 m (P = 0.04; effect size = 0.21) performance increased following HIIT. No changes were found in T _100 m (P = 0.20). Lac_max increased following HIIT (P < 0.01; effect size = 0.43) and decreased after HVT (P < 0.01; effect size = 0.51). VO_2peak increased following both interventions (P < 0.05; effect sizes = 0.46–0.57). The increases in competition performance, T _2,000 m, Lac_max and VO_2peak following HIIT were achieved in significantly less training time (~2 h/week).     

Relationship in humans between spontaneously chosen crank rate and power output during upper body exercise at different levels of intensity

The aim of this study was to assess the relationship between spontaneously chosen crank rate (SCCR) and power output during two upper body exercise tests: firstly, an incremental maximal aerobic power test (T₁), with an initial intensity of 50?W followed by 15-W increases at each subsequent 90-s stage and secondly, a test (T₂) with consecutive exercise periods set at 50%, 60%, 70%, 80%, 110% and 120% of maximal power (P _max) separated by passive recovery periods. Eight nationally and internationally ranked kayakers, aged 20 (SD 2) years, performed the tests. During both T₁ and T₂, mean SCCR values were correlated (r?=?1) and increased significantly (P?1 suggests that it may be used to predict the crank rate which will be chosen in upper body exercise, whatever the intensity. Finally, the results of testing at 110% and 120% of P _max would suggest that a high crank rate (>90?rpm) should be used during the test procedure using supramaximal exercises where accumulated oxygen deficit is calculated, and more particularly when exercise is performed using the upper body.     

Dynaic changes in acid base balance during heatstroke in dogs

The dynamic changes in acid base balance and respiratory metabolism during the development of heatstroke in dogs were studied. Three groups of five unanesthetized dogs each were exposed to different climatic conditions while at rest: A) 24° C, 50% relative humidity (RH); B) 35° C, 35% RH, and C) 45° C, 25% RH, These conditions were maintained for 4 h or until the dogs collapsed. The heatstroke dogs were cooled in tap water bathes and were observed for another 4 h. Dogs of groups A and B did not show any notable changes in rectal temperature (T _re) and acid base balance. All dogs in group C developed heatstroke. Their peak meanT _re (44.1° C) was reached after a mean of 111 min of exposure, with respiratory alkalosis followed by increasingly severe metabolic acidosis aboveT _re of 42° C. At peakT _re mean arterial pH was 7.26. Acidosis increased (pHa=7.17) following cooling, as panting subsided. AtT _re above 42° C blood lactate increased and bicarbonate decreased significantly, attaining mean values of 58 mg% and 8 mEq/l, respectively. Bicarbonate changes correlated linearly with lactate changes. During recovery lactate decreased and blood pH increased approximating normal by the end of the experiment. The results illustrate the body's ability to spontaneously correct arterial pH without therapeutic means.This research was supported by a grant from the United States-Israel Binational Science Foundation (BSF), Jerusalem, Israel     

Sildenafil does not improve steady state cardiovascular hemodynamics, peak power, or 15-km time trial cycling performance at simulated moderate or high altitudes in men and women

Sildenafil improves oxygen delivery and maximal exercise capacity at very high altitudes (≥4,350 m), but it is unknown whether sildenafil improves these variables and longer-duration exercise performance at moderate and high altitudes where competitions are more common. The purpose of this study was to determine the effects of sildenafil on cardiovascular hemodynamics, arterial oxygen saturation (SaO₂), peak exercise capacity (W _peak), and 15-km time trial performance in endurance-trained subjects at simulated moderate (MA; ~2,100 m, 16.2% F_IO₂) and high (HA; ~3,900 m, 12.8% F_IO₂) altitudes. Eleven men and ten women completed two HA W _peak trials after ingesting placebo or 50 mg sildenafil. Subjects then completed four exercise trials (30 min at 55% of altitude-specific W _peak + 15-km time trial) at MA and HA after ingesting placebo or 50 mg sildenafil. All trials were performed in randomized, counterbalanced, and double-blind fashion. Sildenafil had little influence on cardiovascular hemodynamics at MA or HA, but did result in higher SaO₂ values (+3%, p < 0.05) compared to placebo during steady state and time trial exercise at HA. W _peak at HA was 19% lower than SL (p < 0.001) and was not significantly affected by sildenafil. Similarly, the significantly slower time trial performance at MA (28.1 ± 0.5 min, p = 0.016) and HA (30.3 ± 0.6 min, p < 0.001) compared to SL (27.5 ± 0.6 min) was unaffected by sildenafil. We conclude that sildenafil is unlikely to exert beneficial effects at altitudes <4,000 m for a majority of the population.     

Effects of spontaneously chosen crank rate variations on electromyographic responses in sub-maximal arm exercise in inexperienced subjects

The aim of the present study was to compare electromyographic responses during arm exercises with a crank rate chosen spontaneously (T_S) or set at 20% below or above (T_–20, T₊₂₀) the spontaneously chosen crank rate (SCCR). Ten male physical education students performed arm exercises with intensities ranging from 20% to 80% of maximal power. Muscular activity levels were analysed for the biceps brachii and the triceps brachii muscles using integrated rectified surface electromyography (iEMG). All values were presented as the mean and standard deviation. During T_S, the sum of iEMG for the two muscles studied was significantly (P<0.05) lower than during T₊₂₀ for each power output. No significant differences were observed in iEMG values between T_S and T_–20. The hypothesis that SCCR relates to a minimisation of muscle activation during an upper body exercise was not confirmed. Variations superior or inferior to a 20% increase of the iEMG responses do not influence it. Moreover, the selection of crank rates depends on the power output and the SCCR increased significantly (P<0.05) with increasing power output.     

Plantar flexion: an effective training for peripheral arterial disease

This study examined whether a training intervention likely to elicit adaptations in the leg could result in reduced leg pain and increased whole body physical capacity. Twenty-seven peripheral arterial disease (PAD) patients were randomized to either an individual leg plantar flexion training group (TG) training 4 × 4 min intervals at 80% of maximal work rate three times per week for 8 weeks or a control group. The TG significantly increased plantar flexion peak oxygen uptake and power output by 23.5 and 43.9%, respectively. Treadmill peak oxygen uptake (VO_2peak) significantly increased 12.3% in the TG and was associated with a significant increased time to exhaustion of 20.0% when treadmill walking. Eleven of 14 patients no longer reported leg pain limitations at VO_2peak. No differences in cardiac output measured at VO_2peak, or walking economy were observed. Plantar flexion training was effective in increasing VO_2peak and walking performance, and may be a useful strategy in treatment of PAD.     

Maximal power and torque-velocity relationship on a cycle ergometer during the acceleration phase of a single all-out exercise

Seven subjects pedalled on a Monark cycle ergometer as fast as possible for approximately 7 s against four different resistances which corresponded to braking torques (T _B) equal to 19, 38, 57 and 76 N · m at the crank level. Exercise periods were separated by 5-min recovery periods. Pedal velocity was recorded every 50 ms by means of a disc with 360 slots fixed on the flywheel, passing in front of a photo-electric cell linked to a microcomputer which processed the data. Every 50 ms, the time necessary to perform half a pedal revolution (t _1/2) was computed by adding the 50-ms periods necessary to reach 669 slots (the number of slots corresponding to half a pedal revolution). To measuret _1/2 to an accuracy better than 50 ms, this time was computed by a linear interpolation of the time-slot number relationship. Power (P) was averaged duringt ₁₂ by adding the power dissipated against braking torque and the power necessary to accelerate the flywheel. The torque-velocity (T-) relationship was studied during the acceleration phase of a sprint against a single TB by computing every 50 ms the relationship between and T (N · m), equal to the sum ofT _B and the torque necessary to accelerate the flywheel at the same time. The T- relationships calculated from the acceleration phase of a single all-out exercise were linear and similar to the previously described relationships between peak velocity and braking force. These relationships can be expressed as follows: = _0,acc (1 –T/T _0,acc) where is pedal velocity,T the torque exerted on the crank andT _0,acc and _0,acc have the dimensions of maximal torque and maximal velocity respectively. Based on this model, maximal power (P _max,acc) is calculated as 0.257_{0, acc} T _{0, acc}. Maximal powerP _max,acc measured with the acceleration method was independent of braking torqueT _B and slightly higher thanP _max calculated from the relationship between peak velocity andT _B.